An attempt to analyze multi-unit recordings

Abstract

In neurophysiological experiments it is sometimes desirable or inevitable to record signals from several units simultaneously with a single electrode. In either case, one wishes to separate the recorded spike potentials with regard to their sources. A “single” unit must be defined either on the basis of spike wave form, or on an operational basis by means of recurring patterns in spike discharge. The first approach can be and has been pursued by means of special electronic equipment. The second approach usually requires a search for a meaningful operational criterion, and can be aided materially by the use of an appropriate computer system. This note illustrate the use of a computer system in two attempts to analyze complex data in which spike potentials from several neurons were involved. If spike potentials from several units are recorded simultaneously with a single electrode, digital computers with graphic display facilities may be used to advantage to separate the signals from the various units rapidly. Two simple methods for separation are discussed, one using the wave shape, the other using operational criteria. These methods are illustrated by applications to research in the fly and cat central nervous systems.